types: remove the [u_]quad type and replace with [u]int64

All current platforms have a quad type that maps to a 64bit scalar.
But there are platforms where quad maps to a 64bit non-scalar.

Replace quad with int64 in the protocol definitions and the ZDR layer
so that these fields will map to a 64 bit scalar also on those platforms
where quad can not be used.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>